Omnidirectional phase matching of arbitrary processes by radial quasi-periodic nonlinear photonic crystal.

We investigate second-harmonic generation in a nonlinear photonic crystal having radial quasi-periodic order and continuous rotational symmetry. This device enables us to simultaneously phase match different nonlinear interactions in any arbitrary direction of propagation. We have fabricated such a crystal by electric field poling of a magnesium-doped stoichiometric LiTaO(3) and demonstrated frequency doubling of two different pump wavelengths at three different angles.

Engineering two-dimensional nonlinear photonic quasi-crystals.

A known algorithm for modeling quasi-periodic lattices is used to generate two-dimensional quadratic nonlinear photonic quasi-crystals containing a set of desired discrete spectral components. This allows us to fabricate optical devices in which an arbitrary set of nonlinear optical processes can be efficient. We demonstrate this capability by fabricating two devices: a multidirectional single-frequency doubler and a multidirectional, multifrequency doubler that is capable of nearly collinear doubling of cw radiation in the optical communication C band (1530-1570 nm) through angle tuning.

Nonlinear photonic structures for all-optical deflection.

We present a new type of photonic structures in quadratic nonlinear materials that enable efficient and continuous all-optical deflection. The structures are based on two-dimensional modulation of the nonlinear coefficient and consist of a set of symmetric or anti-symmetric arcs that form a periodic pattern in the propagation direction and a chirped pattern in the transverse direction. Stoichiometric lithium tantalite structures were tested by second harmonic generation.